Subclinical ultrasound synovitis in a particular joint is associated with ultrasound evidence of bone erosions in that same joint in rheumatoid patients in clinical remission

Twenty-four consecutive patients with RA in clinical remission according to EULAR criteria (DAS28<2.6) underwent a complete clinical assessment. An experienced sonographer blind to the clinical data performed the US examinations to detect and score signs of joint inflammation and bone erosions from second to fifth metacarpophalangeal (MCP) joints of both hands. All joints were scanned both on dorsal and volar aspects. The second and fifth MCP joints were scanned also in lateral aspects. The patients were mainly female (79.2%), with a mean age of 63.2 years ±12.3 standard deviation (SD) and a mean disease duration of 114.5 months ±53.9 SD. Half of the patients were rheumatoid factor positive and 45.8% were anti-citrullinated protein antibody positive. A total of 192 MCP joints and 480 aspects were assessed. Of these joints, 105 (54.7%) were found inflamed by grey-scale US, 57 (29.7%) were power Doppler (PD) positive, and bone erosions were detected in 42 (21.7%) joints. PD signal was found in 30 (53.6%) of the 56 eroded aspects and in only 41 (9.7%) out of the 424 aspects without bone erosions. Both the GS and PD mean scores were statistically higher in the joints with US bone erosions compared to those without erosions. A higher prevalence of PD signal was found in the joints where bone erosions were detected. This is the first study providing evidence supporting the association between US bone erosions and the persistence of subclinical inflammation in RA patients in clinical remission.